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[Ondrej Certik <ondrej@xxxxxxxxx>]

Hi Juan, you are right, I just changed the summary.

This bug is supper annoying, as I always loose all my work.  How should
we debug it? The best would be to figure out some way to reproduce it
reliably, but that seems like a very hard problem.

So a better way would be to somehow use the memory addresses in the
stacktrace to figure out where in the code the problem happens, and then
add some debug prints over there. Here is the stacktrace, anyone know
how to proceed?


[  4343.791] 0: /usr/bin/X (xorg_backtrace+0x26) [0x4a2626]
[  4343.791] 1: /usr/bin/X (0x400000+0x6219a) [0x46219a]
[  4343.791] 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f491f9a0000+0xfc60) [0x7f491f9afc60]
[  4343.791] 3: /usr/lib/xorg/modules/extensions/librecord.so (0x7f491d355000+0x2920) [0x7f491d357920]
[  4343.791] 4: /usr/bin/X (_CallCallbacks+0x34) [0x432af4]
[  4343.791] 5: /usr/bin/X (WriteToClient+0x21a) [0x461c9a]
[  4343.791] 6: /usr/lib/xorg/modules/extensions/libdri2.so (ProcDRI2WaitMSCReply+0x52) [0x7f491cd3cd82]
[  4343.791] 7: /usr/lib/xorg/modules/extensions/libdri2.so (DRI2WaitMSCComplete+0x59) [0x7f491cd3b479]
[  4343.791] 8: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7f491cae8000+0x25030) [0x7f491cb0d030]
[  4343.791] 9: /lib/x86_64-linux-gnu/libdrm.so.2 (drmHandleEvent+0x108) [0x7f491cf46478]


I have one idea.  The stacktrace above seems to be generated by this
code here:

https://github.com/jolicloud/xorg-
server/blob/2a006327f17f448461aecc715fabef1b0d9caa1f/os/backtrace.c

however, there is a way to obtain way better stacktrace (with files and
line numbers!) using code, that I wrote. So one way to go forward would
be to replace xorg_backtrace() with my own code.


Then, I will introduce some simple bug in the code, like "char *p=NULL; *p=1", to test it. If it works, then I'll simply wait couple days, and once it crashes again, we'll nail it down.

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https://bugs.launchpad.net/bugs/778261

Title:
  Periodic Xorg crashes in intel_drv.so